基于聚多巴胺仿生涂层的分离、吸附、催化多功能膜的制备、优化及应用

发布时间：2018-03-11 17:23

本文选题：多巴胺　切入点：漆酶　出处：《中国科学院大学(中国科学院过程工程研究所)》2017年硕士论文　论文类型：学位论文

【摘要】：生物催化膜将物质选择性传递与化学反应结合,可以极大地提高反应效率,在医药、食品、水处理等领域应用前景广泛。然而目前生物催化膜制备过程中存在的载酶率不高、酶活保持低和膜本身性能下降等问题限制了其应用。针对上述问题,本论文重点研究了同时具备分离、吸附、催化功能的多功能膜的制备及其在水处理过程的应用。研究内容和成果主要分为以下两个部分:(1)受到贻贝粘蛋白和细胞膜结构的启发,将漆酶通过逆向过滤的方式包埋在纳滤膜支撑层内,再利用聚多巴胺(PDA)仿生涂层将漆酶封装在膜内,制备了同时具有截留、催化、吸附三种功能的多功能膜,并将其应用于水中微量污染物的去除。以去除水中双酚A(BPA)为例(原料液中BPA浓度为10mg.L-1),NF270多功能膜对BPA的去除率达到84.3±7.3%,远远高于传统的芬顿氧化(BPA去除率55%)。对其多功能协同作用机制的研究表明,纳滤膜本身具有的截留功能截留部分污染物,减少了酶催化负荷;而膜以及PDA涂层的吸附功能将未被截留的微量污染物在膜内富集并且延长了底物与酶分子的反应时间,进而大大提高酶促反应效率;同时生物酶的催化功能打破了膜材料"吸附饱和"的限制,使得"吸附-催化"过程连续进行,且协同效应的存在大大提高了整体效果。(2)为了解决多功能膜在长期使用过程中由于PDA涂层不够致密导致的酶泄露问题,进一步提高载酶量和酶活力,分别利用多巴胺/聚乙烯亚胺(DA/PEI)和多巴胺/铜离子(DA/Cu2+)共沉淀方法在载酶纳滤膜支撑层内形成新型仿生涂层。研究结果表明共沉淀不仅缩短DA自聚时间,增强PDA涂层的均一性和稳定性,还极大地降低酶泄露,增加封装效率,提高酶活性。此外,采用该种方法制备的多功能膜,其特殊的"分离层-漆酶-支撑层/封装层"三明治结构使得该多功能膜两面均具有催化活性,可以利用其构建双面酶膜反应器(EMR),高效去除水中污染物,其中以DA/Cu2+共沉淀制备的多功能膜构建的EMR具有最高的BPA去除率,且由于流通模式下的强制对流有效移除产物,打破膜稳定性与去除率之间平衡,EMR的使用稳定性得以大幅度提高。研究表明通过调控多功能膜的载酶量、固定化酶位置、酶活性以及底物/产物传质,可以优化EMR对微量污染物的去除效率和稳定性。本研究不仅提出了一种新的生物催化膜制备方法和多功能膜新概念,解决了传统分离膜对水中微量污染物去除效率不高、生物催化膜稳定性不佳等问题,为生物催化膜的制备和应用打开了新思路,而且制备的多功能膜和双面EMR在深度尾水处理及家用净水器上具有较大的应用潜力。
[Abstract]:Biocatalysis membrane can greatly improve the reaction efficiency by combining the selective transport of substances with chemical reaction, and has a wide application prospect in medicine, food, water treatment and other fields. However, the enzyme carrier rate in the preparation process of biocatalysis membrane is not high at present. The low activity of enzyme and the degradation of membrane properties limit its application. In view of the above problems, this paper focuses on simultaneous separation, adsorption, and so on. Preparation of catalytic multifunctional membrane and its application in water treatment. The research contents and results are divided into the following two parts: 1) inspired by mussel mucin and membrane structure. The laccase was encapsulated in the supporting layer of nanofiltration membrane by reverse filtration, and then encapsulated in the membrane by polydopamine PDA-bionic coating. The multifunctional membrane with three functions of interception, catalysis and adsorption was prepared. It was applied to the removal of micro-pollutants in water. Take the removal of bisphenol A and BPA in water as an example. (the concentration of BPA in the feedstock solution is 10 mg 路L ~ (-1) BPA). The removal rate of BPA by NF270 multifunctional membrane is 84.3 卤7.3%, which is much higher than that of traditional Fenton oxidation (55%). Studies of synergistic mechanisms show that, Nanofiltration membrane itself has the function of intercepting some pollutants, which reduces the catalytic load of enzyme, while the adsorption function of membrane and PDA coating enriches the unintercepted trace pollutants in the membrane and prolongs the reaction time of substrate and enzyme molecule. At the same time, the catalytic function of biological enzymes broke the limit of "adsorption saturation" of membrane materials and made the "adsorption-catalysis" process go on continuously. In order to solve the problem of enzyme leakage caused by the lack of compactness of PDA coating during the long-term use of multifunctional membrane, the amount and activity of enzyme carrier were further increased. A novel biomimetic coating was formed in the supporting layer of enzyme carrier nanofiltration membrane by using dopamine / polyvinyleneimide (DA / PEI) and dopamine / copper ion (DA / Cu ~ (2)) coprecipitation, respectively. The results show that coprecipitation not only shortens the time of DA self-polymerization. Enhancing the homogeneity and stability of PDA coating can greatly reduce enzyme leakage, increase encapsulation efficiency and increase enzyme activity. The special sandwich structure of "separating layer laccase-supporting layer / encapsulation layer" makes the multifunctional membrane have catalytic activity on both sides. It can be used to construct a bihedral enzyme membrane reactor (EMRs) to efficiently remove pollutants in water. The EMR prepared by multifunctional membrane prepared by DA/Cu2 coprecipitation has the highest removal rate of BPA, and because of the forced convection in the flow mode, the product can be removed effectively. The stability of EMR was greatly improved by changing the balance between membrane stability and removal efficiency. It was found that the enzyme activity and substrate / product mass transfer were regulated by regulating the enzyme load, immobilized enzyme location, enzyme activity and substrate / product mass transfer. This study not only proposed a new method of preparing biocatalysis membrane and a new concept of multifunctional membrane, but also solved the low removal efficiency of trace pollutants in water by traditional separation membrane. The instability of biocatalysis membrane has opened a new way for the preparation and application of biocatalysis membrane, and the multifunctional membrane and double-sided EMR have great application potential in deep tail water treatment and household water purifier.
【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2;TQ085.4

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